TY - JOUR
T1 - Enhanced reflex response to baroreceptor deactivation in subjects with tilt-induced syncope
AU - Pitzalis, Mariavittoria
AU - Parati, Gianfranco
AU - Massari, Francesco
AU - Guida, Pietro
AU - Di Rienzo, Marco
AU - Rizzon, Brian
AU - Castiglioni, Paolo
AU - Iacoviello, Massimo
AU - Mastropasqua, Filippo
AU - Rizzon, Paolo
PY - 2003/4/2
Y1 - 2003/4/2
N2 - OBJECTIVES: We sought to evaluate whether changes in resting baroreflex control of heart rate are a distinctive feature of healthy subjects with a history of syncope prone to a positive tilt-test response. BACKGROUND: The mechanisms involved in the pathogenesis of vasovagal syncope (VVS) are still poorly understood; in particular, the contribution of arterial baroreflex control of heart rate is matter of discussion. METHODS: A passive tilt-table test was performed in 312 consecutive, otherwise healthy subjects (age 36 ± 15 years) with unexplained syncope and 100 control subjects. At baseline, spontaneous baroreflex sensitivity (BRS; ms/mm Hg) and the baroreflex effectiveness index (BEI) were assessed using the sequence method. RESULTS: The study population showed normal baroreflex function. Tilt-induced VVS in 94 subjects who were younger than both the tilt-negative and control subjects (30 ± 14, 38 ± 15, and 37 ± 14 years, respectively; p = 0.00005) showed greater BRS (17.4 ± 9.8, 13.2 ± 7.9, and 12.8 ± 8.2 ms/mm Hg, respectively; p = 0.0001), but had a similar BEI (0.59 ± 0.18, 0.56 ± 0.19, and 0.58 ± 0.2, respectively; p = NS). On Cox multivariate analysis, the occurrence of VVS during tilt was inversely related to age (hazard ratio 0.97; p = 0.0004) and directly related to the BRS slope of sequences, implying a baroreceptor deactivation (hazard ratio 1.05; p = 0.02), but not of sequences characterized by arterial baroreceptor stimulation. CONCLUSIONS: Subjects with tilt-induced VVS showed greater resting BRS but had a normal BEI. The enhanced reflex tachycardic response to arterial baroreceptor deactivation at rest may represent a characteristic feature of subjects prone to tilt-induced VVS.
AB - OBJECTIVES: We sought to evaluate whether changes in resting baroreflex control of heart rate are a distinctive feature of healthy subjects with a history of syncope prone to a positive tilt-test response. BACKGROUND: The mechanisms involved in the pathogenesis of vasovagal syncope (VVS) are still poorly understood; in particular, the contribution of arterial baroreflex control of heart rate is matter of discussion. METHODS: A passive tilt-table test was performed in 312 consecutive, otherwise healthy subjects (age 36 ± 15 years) with unexplained syncope and 100 control subjects. At baseline, spontaneous baroreflex sensitivity (BRS; ms/mm Hg) and the baroreflex effectiveness index (BEI) were assessed using the sequence method. RESULTS: The study population showed normal baroreflex function. Tilt-induced VVS in 94 subjects who were younger than both the tilt-negative and control subjects (30 ± 14, 38 ± 15, and 37 ± 14 years, respectively; p = 0.00005) showed greater BRS (17.4 ± 9.8, 13.2 ± 7.9, and 12.8 ± 8.2 ms/mm Hg, respectively; p = 0.0001), but had a similar BEI (0.59 ± 0.18, 0.56 ± 0.19, and 0.58 ± 0.2, respectively; p = NS). On Cox multivariate analysis, the occurrence of VVS during tilt was inversely related to age (hazard ratio 0.97; p = 0.0004) and directly related to the BRS slope of sequences, implying a baroreceptor deactivation (hazard ratio 1.05; p = 0.02), but not of sequences characterized by arterial baroreceptor stimulation. CONCLUSIONS: Subjects with tilt-induced VVS showed greater resting BRS but had a normal BEI. The enhanced reflex tachycardic response to arterial baroreceptor deactivation at rest may represent a characteristic feature of subjects prone to tilt-induced VVS.
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U2 - 10.1016/S0735-1097(03)00050-0
DO - 10.1016/S0735-1097(03)00050-0
M3 - Article
C2 - 12679218
AN - SCOPUS:0037414078
VL - 41
SP - 1167
EP - 1173
JO - Journal of the American College of Cardiology
JF - Journal of the American College of Cardiology
SN - 0735-1097
IS - 7
ER -